JP2005262082A - Hydrogen separation membrane, production method therefor, and hydrogen separation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a hydrogen separation membrane capable of preventing constitutional elements of a porous sintered metal from diffusing to a palladium thin film even when the hydrogen separation membrane is composed of a support consisting of the porous sintered metal and the palladium (including a palladium alloy) thin film as the constitutional elements. <P>SOLUTION: The hydrogen separation membrane is composed of the porous support consisting of the sintered metal; a thin film formed on the surface of the support, and consisting of a metal not forming a solid solution with constitutive elements of the sintered metal; and the thin film of palladium or the palladium alloy formed on the thin film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydrogen separation membrane, a method for producing the same, and a method for separating hydrogen.

  A palladium (including palladium alloy) thin film has a hydrogen selective permeability and has been used as a component of a conventional hydrogen separation membrane. For example, Patent Document 1 discloses a hydrogen separation membrane in which a porous ceramic such as alumina is used as a support and a palladium or palladium alloy thin film is formed on the surface thereof by a plating method. Such a hydrogen separation membrane has the characteristics that the smaller the thickness of the palladium thin film, the higher the hydrogen permeation rate and the lower the amount of palladium used as an expensive noble metal.

  However, in a hydrogen separation membrane using palladium (including a palladium alloy), palladium is generally brittle at a use temperature of 300 ° C. or lower, and therefore needs to be used at a temperature exceeding 300 ° C. Further, when ceramics are used as the support, it is difficult to bond the hydrogen separation membrane to the metal, which hinders mounting on industrial equipment.

  As for the latter problem, for example, by using a porous sintered metal conventionally used for a gas filter or the like as a support, it is possible to facilitate joining to the metal.

However, in the case of a hydrogen separation membrane in which a porous sintered metal such as stainless steel is used as a support and a palladium or palladium alloy thin film is directly formed on the surface thereof, especially when used at a temperature of 500 ° C. or higher, porous sintering It is known that constituent elements such as iron, nickel, and chromium contained in metal diffuse into palladium or palladium alloy thin film over time and degrade the performance of the hydrogen separation membrane (see Non-Patent Document 1).
Japanese Patent Laid-Open No. 05-1371979 Structurally stable composite Pd-Ag alloy membranes: Introduction of a diffusion barrier, Thin Solid Films, 286, 72-79 (1996)

  The present invention is a hydrogen separation in which diffusion of constituent elements of a porous sintered metal into a palladium thin film is prevented even when a support made of a porous sintered metal and a palladium (including palladium alloy) thin film are used as constituent elements. The main purpose is to provide a membrane.

  As a result of intensive studies to achieve the above object, the present inventor formed a sintered metal constituent element and a solid solution as a diffusion barrier film for the sintered metal constituent element on the surface of the porous support made of sintered metal. In the case where a thin film made of a metal that is not used is formed and a thin film of palladium or palladium alloy is formed on the thin film, the present inventors have found that the above object can be achieved and have completed the present invention.

That is, the present invention relates to the following hydrogen separation membrane, a production method thereof, and a hydrogen separation method.
1. Porous support made of sintered metal, thin film made of metal that does not form a solid solution with constituent elements of the sintered metal formed on the surface of the support, and thin film of palladium or palladium alloy formed on the thin film A hydrogen separation membrane comprising:
2. At least selected from the group consisting of metals, metal oxides, ceramics and their precursor components in the voids present on the surface of the porous support or on the thin film surface made of a metal that does not form a solid solution with the constituent elements of the sintered metal Item 2. The hydrogen separation membrane according to Item 1, filled with one kind.
3. Item 3. The hydrogen separation membrane according to Item 1 or 2, wherein the metal that does not form a solid solution with the constituent element of the sintered metal is at least one selected from the group consisting of silver, gold, indium, tin, and lead.
4). A thin film made of metal that does not form a solid solution with the constituent elements of the sintered metal is formed on the surface of the porous support made of sintered metal, and then a thin film of palladium or palladium alloy is formed on the thin film. A method for producing a hydrogen separation membrane.
5). Group consisting of metal fine particles, metal oxide fine particles, ceramic fine particles, and precursor fine particles of these components in the voids existing on the surface of the porous support or on the thin film surface made of a metal that does not form a solid solution with the constituent elements of the sintered metal Item 5. The method according to Item 4, further comprising a step of filling at least one kind of fine particles selected from the above.
6). Item 6. The method for producing a hydrogen separation membrane according to Item 4 or 5, wherein the metal that does not form a solid solution with the constituent element of the sintered metal is at least one selected from the group consisting of silver, gold, indium, tin and lead.
7). The hydrogen-containing mixed gas is present on one side isolated by the hydrogen separation membrane according to any one of Items 1 to 3, and the hydrogen partial pressure on the other side is less than the hydrogen partial pressure on the hydrogen-containing mixed gas side. A method for separating hydrogen from a hydrogen-containing gas mixture.

Hereinafter, the hydrogen separation membrane, the production method thereof, and the hydrogen separation method of the present invention will be described.

  In the following description, unless otherwise specified, palladium includes the meaning of a palladium alloy.

Hydrogen separation membrane and method for producing the same The hydrogen separation membrane of the present invention is a porous support made of sintered metal, and a thin film made of metal that does not form a solid solution with constituent elements of the sintered metal formed on the surface of the support. And a thin film of palladium or palladium alloy formed on the thin film.

  As described above, in the hydrogen separation membrane of the present invention, a thin film (also referred to as a diffusion barrier membrane) made of a metal that does not form a solid solution with the constituent elements of the sintered metal is formed on the surface of the porous support made of the sintered metal. Therefore, even if the hydrogen separation membrane is used under a high temperature condition of 500 ° C. or more, it is possible to prevent the sintered metal constituent element from diffusing into the palladium thin film. This is because the sintered metal constituent element cannot be dissolved (dissolved) in the diffusion barrier film-forming metal and does not enter the diffusion barrier film, so that the constituent element is prevented from diffusing into the palladium thin film. Hereinafter, each component of the hydrogen separation membrane of the present invention will be described.

  In the hydrogen separation membrane of the present invention, a porous support made of sintered metal is used.

  The sintered metal is not particularly limited as long as it is porous and can easily permeate hydrogen, but generally has a volume-based porosity of 10 to 60%, preferably about 20 to 50%. The average pore diameter may be 0.1 to 10 μm, preferably about 0.5 to 5 μm. The porosity and average pore diameter are values measured by a mercury intrusion method.

  Specific examples include stainless steel, hastelloy alloy, inconel alloy, nickel, and nickel alloy having the above porosity and average pore diameter. Among these, stainless steel is particularly preferable in terms of economy.

  These sintered metals contain various constituent elements. For example, in the case of stainless steel, iron, nickel, chromium and the like are included. If it is a Hastelloy alloy, it contains nickel, chromium and molybdenum. Inconel alloys include nickel, chromium, iron, and molybdenum. If it is a nickel alloy, nickel, chromium, and cobalt are contained. The atomic radius of these sintered metal constituent elements is approximately 0.127 nm or less.

  The shape of the porous support is not particularly limited, and a shape conventionally used as a support for a hydrogen separation membrane can be widely adopted. Examples thereof include a plate shape, a cylindrical shape, and a cylindrical shape with one end closed. The thickness of the support (if it is a cylinder, the difference between the outer diameter and the inner diameter) is not particularly limited, and is usually about 0.2 to 10 mm, preferably about 1 to 5 mm.

  In the hydrogen separation membrane of the present invention, a thin film (diffusion prevention membrane) made of a metal that does not form a solid solution with constituent elements of the sintered metal is formed on the surface of the porous support made of the sintered metal. When this diffusion blocking film is present between the support and the palladium thin film described later, diffusion of the sintered metal constituting element into the palladium thin film is prevented.

  As the metal forming the diffusion barrier film, it is necessary to use a metal that does not dissolve (dissolve) the sintered metal constituent element. As the metal that does not form a solid solution with the sintered metal constituent element, a metal having a larger atomic radius than the sintered metal constituent element may be used. As for the difference in atomic radius, regardless of whether substitutional solid solution or interstitial solid solution is assumed, there is a difference that the lattice state becomes very unstable due to the difference in atomic radius and cannot exist as a solid solution. Good. If there is such a difference in atomic radius, the sintered metal constituent element does not form a solid solution in relation to the diffusion-preventing film-forming metal (that is, does not enter the diffusion-preventing film), and as a result, the sintered metal constituent Diffusion of elements into the palladium thin film can be prevented.

  Specifically, examples of the sintered metal constituting element include iron, nickel, chromium, and molybdenum as described above, and the atomic radius thereof is approximately 0.127 nm or less. Therefore, any metal having an atomic radius exceeding 0.137 nm (corresponding to the Pd atomic radius) out of atomic radii larger than 0.127 nm can be used as a diffusion barrier film-forming metal. However, since a larger atomic radius difference is more effective for preventing solid solution, it is preferable to use a metal having an atomic radius of 0.144 nm or more. The upper limit of the atomic radius of the diffusion barrier film-forming metal is not particularly limited, but is usually about 0.175 nm, preferably about 0.166 nm.

  The diffusion-preventing film-forming metal is not particularly limited as long as it can prevent solid-solution of the sintered metal constituent elements and does not adversely affect the porous support and the palladium thin film described later. Specific examples include silver, gold, indium, tin, lead, and the like. All of these metals have an atomic radius of 0.144 nm or more. Among these, silver and gold are preferable from the viewpoint of affinity with palladium, and silver is particularly preferable in consideration of cost.

  The method for forming the diffusion barrier film is not particularly limited, and examples thereof include an electroless plating method, an electroplating method, and a paste coating method. The plating method is not particularly limited, and an electroplating method or an electroless plating method can be applied, and may be appropriately selected according to the type and shape of the porous support. Specific plating conditions are not particularly limited, and plating may be performed according to known conditions using a known plating bath capable of forming a target metal thin film. Further, in the method of applying the paste, for example, the diffusion barrier film-forming metal fine particles are mixed with a high viscosity organic material such as an ethylene glycol polymer to form a paste, and the paste is applied to the surface of the porous support, followed by heat treatment. Just do it. A plurality of these diffusion barrier film forming methods can be combined as necessary.

  The diffusion barrier membrane may be formed on the entire surface of the porous support, but usually it may be formed in a range where hydrogen can permeate when used as a hydrogen separation membrane depending on the shape of the porous support. . For example, when a plate-like porous support is used, a diffusion prevention film may be formed in a range where hydrogen gas permeates, and when a cylindrical porous support is used, for example, the outer surface A diffusion blocking film may be formed on the substrate.

  When forming a diffusion barrier film by a plating method, a method in which a plating solution is pressed into the pores from one surface of the porous support, one surface of the porous body is brought into contact with the plating solution, and the other Adopting a method of sucking the plating solution by reducing the pressure on the surface side can improve the adhesion of the diffusion barrier film to be formed.

  The thickness of the diffusion barrier film formed by these methods is not particularly limited as long as the surface pores of the porous support are not significantly covered, but is usually 0.1 μm or more, preferably 0.2 μm or more. If it is less than 0.1 μm, the diffusion of the sintered metal constituting element into the palladium thin film may not be prevented. The upper limit of the thickness of the diffusion barrier film is not particularly limited, but is usually about 5 μm, preferably about 2 μm, from the viewpoint of preventing clogging of the surface pores.

  In order to improve the adhesion of the diffusion barrier film to the porous support, a diffusion barrier film may be formed after the base film is formed on the surface of the porous support. As the base film, for example, a thin film made of nickel, copper or the like can be used. Such a base film may be formed by electroplating or the like. Although the thickness of a base film is not specifically limited, Usually, 0.1-1 micrometer, Preferably it is about 0.2-0.5 micrometer.

  In the hydrogen separation membrane of the present invention, a palladium thin film is formed on the diffusion barrier membrane. As described above, the palladium thin film includes the meaning of a palladium alloy thin film. The alloy component is not particularly limited, and examples thereof include at least one selected from the group consisting of silver, gold, rhodium, ruthenium, copper and nickel. The proportion of palladium in such a palladium alloy is not particularly limited, but is usually 50% or more, preferably about 60% or more.

  The method for forming the palladium thin film is not particularly limited, and for example, an electroplating method, an electroless plating method, a chemical vapor deposition method, or the like can be applied. These methods can be applied in combination of two or more. However, by directly depositing palladium on the surface of a porous support (deposited material) on which a diffusion barrier film is formed by chemical vapor deposition, it is possible to form voids in the deposited material. Is not preferable because of too much. Therefore, it is preferable to combine palladium deposition by chemical vapor deposition for the purpose of reducing defects in the plating film after plating palladium on the surface of the porous support on which the diffusion barrier film is formed by plating. Moreover, it is practical to combine in this way.

  The plating conditions in the electroplating method and the electroless plating method are not particularly limited, and plating is performed according to known conditions using a known plating bath capable of forming a target palladium, a palladium alloy, and a metal other than palladium. Can be done. The plating film of a metal other than palladium is used, for example, to form a palladium alloy thin film by laminating the palladium plating film and then heat-treating the whole to form an alloy.

  In addition, when a palladium thin film is formed by plating, a method in which a plating solution is pressed into the pores from one surface of a porous support (plating object) on which a diffusion barrier film is formed, one of the plating objects If a method of bringing the surface into contact with the plating solution and reducing the pressure on the other surface and sucking the plating solution is used, the adhesion of the formed palladium thin film can be improved. At this time, if the plating solution is vibrated by ultrasonic waves, the plating solution can be penetrated into the inside of the pores.

The vapor deposition conditions by the chemical vapor deposition method are not particularly limited, and a known chemical vapor deposition method can be applied. For example, a palladium compound having a vapor pressure of about 1.3 × 10 ^{−2 to} 1.3 × 10 ⁵ Pa and evaporating at about 40 to 250 ° C., preferably about 50 to 200 ° C., is vaporized. Then, palladium is deposited on the deposition target by supplying it to the deposition target and decomposing it after the deposition. When palladium deposition by such chemical vapor deposition is performed after plating palladium by plating, defects during palladium plating are alleviated, and gas leakage other than hydrogen is prevented when used as a hydrogen separation membrane. Thus, the selective permeability of hydrogen can be improved.

Specific examples of such a palladium compound include bis (acetylacetonato) palladium (II), bis (hexafluoroacetylacetonato) palladium (II), palladium acetate, potassium bis (oxalato) palladate, bis (dithiooxalato). ) Potassium palladiumate, tetraamminepalladium chloride, bis (ethylenediamine) palladium chloride, bis (2,2′-bipyridine) palladium perchlorate, bis (1,10-phenanthroline) palladium perchlorate, bis (dimethyl Glyoximato) palladium (II), [Pd (PCH ₃ ) ₄ ], [Pd (PPh ₂ C ₂ H ₃ PPh ₂ ) ₂ ] (wherein Ph represents a phenyl group), dichlorobis (η-ethylene) Palladium (II), tetrachlorodi (η-ethylene) palladium II), carbonyl dichloropalladium (II), dicarbonyl dichloropalladium (II), and the like.

  The vaporization temperature of the palladium compound at the time of chemical vapor deposition is not particularly limited as long as it is a temperature at which the palladium compound to be used is vaporized, and can be appropriately set according to the kind of the palladium compound. The temperature is usually about 40 to 250 ° C, preferably about 50 to 200 ° C. The vaporized palladium compound may be guided to a deposition target (for example, a palladium thin film) accompanied by a carrier gas. As the carrier gas, for example, an inert gas such as nitrogen, helium, or argon can be used, but in some cases, a reactive gas such as hydrogen or oxygen may be used as the carrier gas.

  The vapor deposition temperature on the palladium thin film may be equal to or higher than the vaporization temperature of the palladium compound, and is usually about 40 to 600 ° C, preferably about 50 to 400 ° C. When the palladium compound is thermally decomposed immediately after vapor deposition, the vapor deposition temperature is preferably about 200 to 600 ° C, more preferably about 250 to 400 ° C.

  The vapor deposition time is not particularly limited and can be appropriately set according to the desired palladium deposition amount, but is usually about 0.5 to 24 hours, preferably about 1 to 10 hours.

  In addition, when palladium is vapor-deposited, one surface of the deposition target is brought into contact with the vaporized palladium compound, and the pressure on the other surface side is made lower than the pressure on the side where the vaporized palladium compound is in contact with the palladium compound. Can be vapor-deposited while being distributed efficiently. For example, after forming a palladium thin film on the outside of a tubular porous support with one end sealed by plating, the inside of the support is reduced in pressure, and the outer surface (deposition surface) of the support is vaporized. By contacting with the palladium compound, the vaporized palladium compound can be preferentially guided to the defective portion of the palladium plating, and the palladium compound can be more reliably deposited on the plating defect.

  Further, heat treatment, reduction treatment, or the like may be performed as necessary to completely adhere the deposited palladium. Although the heating temperature in heat processing can be suitably set according to the kind etc. of palladium compound, it is preferable to set it as about 200-600 degreeC, and it is more preferable to set it as 250-400 degreeC. The heat treatment is usually performed in an oxygen-containing atmosphere such as in the air. The heating time is usually about 1 to 5 hours. The reduction treatment can usually be performed by heating in a reducing gas atmosphere. As the reducing gas, for example, a reducing gas such as hydrogen, carbon monoxide, or methanol can be used. The reduction temperature can be appropriately set according to the kind of the palladium compound, but is preferably about 100 to 600 ° C, more preferably about 200 to 500 ° C. The time for the reduction treatment is usually about 30 minutes to 5 hours. Only one of these heat treatment and reduction treatment may be performed, or both treatments may be performed.

  In addition, in the case where palladium and a metal other than palladium are deposited separately for the purpose of forming a palladium alloy thin film, in order to promote the alloying, in a vacuum; in an inert gas such as nitrogen, argon or helium Heat treatment is performed in hydrogen or the like. The heat treatment temperature is usually 300 to 900 ° C., preferably 400 to 800 ° C., more preferably 500 to 700 ° C. The heat treatment time can be appropriately set according to the kind of deposited metal, the heat treatment temperature, and the like. If the heat treatment becomes excessive, the diffusion barrier film and the palladium film thereon are remarkably alloyed, and the function of the diffusion barrier film may be impaired. Therefore, the heat treatment conditions are adjusted within a range in which such alloy formation does not occur. There is a need. Thereby, the target palladium alloy thin film is obtained.

  The palladium thin film may be formed so as to cover the diffusion barrier film formed on the surface of the porous support. Usually, it forms in the range which hydrogen permeate | transmits when using as a hydrogen separation membrane according to the shape of a porous support body. For example, when using a plate-like porous support, a palladium thin film is formed in a range where hydrogen gas is desired to pass. When using a cylindrical porous support, for example, a palladium thin film is formed on the outer surface. Is formed.

  The thickness of the palladium thin film formed by these methods is usually about 1 to 20 μm, preferably about 2 to 10 μm. If the thickness is less than 1 μm, the thin film defects may increase, and if it exceeds 20 μm, the amount of hydrogen permeation decreases and the economy is impaired.

  In the hydrogen separation membrane of the present invention, when pores having a surface pore diameter of 10 μm or more are present on the surface of the porous support, the pores are not exposed when the palladium thin film is formed after the formation of the diffusion barrier membrane. It can be a defect. In order to eliminate such surface defects, for example, after formation of the diffusion barrier film, metal fine particles, metal oxide fine particles, ceramic fine particles, and these components (metal, metal, metal) are formed in voids existing on the surface of the barrier film. It is effective to fill at least one kind of fine particles selected from the group consisting of precursor fine particles of oxides and ceramics and to reduce the average pore diameter of the surface pores. The formation of the palladium thin film may be performed on the surface of the diffusion barrier film after filling.

  Such filling of the fine particles can be performed on the pores on the surface of the porous support before the formation of the diffusion barrier film. In this case, however, the diffusion barrier film-forming metal adheres to the fine particles after the filling. As a result, gas permeability may be lowered, and therefore it is preferable to fill fine particles after the formation of the diffusion barrier film. The filling amount is not particularly limited, but usually an amount capable of reducing the porosity of the sintered metal layer present in the region of about 10 μm from the surface to 20% or less is preferable.

  Examples of the metal fine particles include fine particles of silver, palladium, gold and the like. Examples of the metal oxide fine particles include fine particles of aluminum oxide, zirconium oxide, cerium oxide, zinc oxide, titanium oxide and the like. Examples of the ceramic fine particles include fine particles of silica, silicon nitride, aluminum nitride, silicon carbide, and the like. Examples of the precursor fine particles of these components (metal, metal oxide and ceramic) include, for example, silver hydroxide, palladium hydroxide, gold hydroxide, aluminum hydroxide, zirconium hydroxide, cerium hydroxide, zinc hydroxide, water Examples thereof include fine particles such as titanium oxide and silica gel. Since these fine particles are fine particles that do not adversely affect the palladium thin film, they are suitable for filling. The effective particle diameter of the fine particles is not particularly limited as long as it is smaller than the diameter of the pores to be filled. Note that these fine particles may be removed from the fine particle state by a heat treatment performed at the time of forming a palladium thin film or the like to become a lump of metal, metal oxide, ceramics, or the like.

  The method for filling the fine particles is not particularly limited. For example, a method of press-fitting into a pore to be filled with a dispersion containing fine particles, one surface of the object to be filled is brought into contact with the dispersion, and the other surface is decompressed. If a method of sucking the dispersion liquid is employed, the deposition of fine particles can be promoted. At this time, if the dispersion liquid or the filling object is vibrated by ultrasonic waves, the fine particles can be efficiently deposited to the inside of the voids (pores).

  Further, when an electroless plating method is adopted for forming the palladium thin film, a catalyst-imparting agent for plating may be mixed in a dispersion containing fine particles. Thereby, since deposition of fine particles and application of a catalyst for plating can be performed at the same time, the production process of the hydrogen separation membrane can be reduced.

  If a method of filling such fine particles into the pores is adopted, surface defects of the hydrogen separation membrane can be reduced, so that the surface pore diameter of the pores existing on the porous support surface is less than 10 μm. Even in this case, this method may be applied.

Hydrogen Separation Method The hydrogen separation membrane of the present invention can be used to separate only hydrogen from a gas mixture containing hydrogen according to a conventional method. For example, a hydrogen-containing mixed gas is positioned on one side separated by the hydrogen separation membrane, one surface of the hydrogen separation membrane is brought into contact with the hydrogen-containing gas, and the hydrogen partial pressure on the other surface side is mixed with the hydrogen-containing mixture. It may be less than the hydrogen partial pressure on the gas side. Thereby, hydrogen selectively permeates through the hydrogen separation membrane, and only hydrogen on the hydrogen-containing mixed gas side can be moved to the opposite side for separation. In this case, the temperature of the hydrogen separation membrane is usually 200 to 700 ° C., preferably about 300 to 600 ° C. If the temperature is too low, embrittlement in the palladium or palladium alloy thin film tends to occur, and if the temperature is too high, the film tends to deteriorate.

  The hydrogen separation membrane of the present invention has a sintered metal structure because a thin film (diffusion prevention film) made of a metal that does not form a solid solution with a sintered metal constituent element is formed on the surface of a porous support made of sintered metal. The element cannot enter the diffusion barrier film, and even when the hydrogen separation membrane is used under high temperature conditions (particularly 500 ° C. or higher), the diffusion of the sintered metal constituting element into the palladium thin film is prevented. Therefore, it is thermally stable as compared with known hydrogen separation membranes.

  In addition, since a support made of sintered metal is used, it is easy to mount on industrial equipment and is mechanically stable.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to the examples.

Production Example 1
A silver thin film (film thickness: 1 μm) was formed by electroless plating on the surface (the outer surface of the tube) of a cylindrical stainless steel sintered metal tube (inner diameter: 7 mm, outer diameter: 10 mm, average surface pore diameter: 1 μm) sealed on one side. . Next, a palladium thin film (film thickness 5 μm) was formed thereon by electroless plating. Further, a palladium thin film (film thickness 5 μm) was formed by electroplating to increase the palladium film thickness, and finally the palladium film thickness was 10 μm.

  Next, the metal tube on which the palladium thin film was formed was dried at 120 ° C. for 10 hours and then heat-treated in an argon stream at 500 ° C. for 5 hours to produce a hydrogen separation membrane.

Production Example 2
A silver thin film (thickness 0.3 μm) is formed by electroplating on the surface (the outer surface of the tube) of a cylindrical stainless steel tube (inner diameter 7 mm, outer diameter 10 mm, average surface pore diameter 5 μm) sealed on one side did. Next, a dispersion liquid in which aluminum hydroxide fine particles are dispersed in a catalyst imparting agent for electroless plating is sucked by reducing the pressure inside the sintered metal tube, and the aluminum hydroxide fine particles are put into the surface pores of the sintered metal tube. Deposited. Thereafter, a palladium thin film (film thickness: 8 μm) was formed thereon by electroless plating.

  Next, the metal tube on which the palladium thin film was formed was dried at 120 ° C. for 10 hours and then heat-treated in an argon stream at 500 ° C. for 5 hours to produce a hydrogen separation membrane.

Production Example 3
A silver thin film (thickness 0.3 μm) is formed by electroplating on the surface (the outer surface of the tube) of a cylindrical stainless steel tube (inner diameter 7 mm, outer diameter 10 mm, average surface pore diameter 5 μm) sealed on one side did. Next, a dispersion liquid in which aluminum hydroxide fine particles are dispersed in a catalyst imparting agent for electroless plating is sucked by reducing the pressure inside the sintered metal tube, and the aluminum hydroxide fine particles are put into the surface pores of the sintered metal tube. Deposited. Thereafter, a palladium thin film (film thickness: 3 μm) was formed thereon by electroless plating.

  Next, the metal tube on which the palladium thin film was formed was dried at 120 ° C. for 10 hours and then heat-treated in an argon stream at 500 ° C. for 5 hours to produce a hydrogen separation membrane.

Production Example 4
Forming a thin gold film (thickness 0.5 μm) by electroplating on the surface (outer surface of the tube) of a cylindrical stainless steel tube (inner diameter 7 mm, outer diameter 10 mm, average surface pore diameter 5 μm) sealed on one side did. Next, a dispersion liquid in which aluminum hydroxide fine particles are dispersed in a catalyst imparting agent for electroless plating is sucked by reducing the pressure inside the sintered metal tube, and the aluminum hydroxide fine particles are put into the surface pores of the sintered metal tube. Deposited. Thereafter, a palladium thin film (film thickness: 3 μm) was formed thereon by electroless plating. Further, a palladium / silver alloy thin film (film thickness: 2 μm) was formed thereon by electroplating.

  Next, the metal tube on which the palladium / silver alloy thin film was formed was dried at 120 ° C. for 10 hours and then heat-treated in an argon stream at 500 ° C. for 5 hours to produce a hydrogen separation membrane.

Comparative production example 1
A cylindrical stainless steel sintered tube (inner diameter 7 mm, outer diameter 10 mm, average surface pore diameter 5 μm) sealed on one side was prepared. Next, a dispersion liquid in which aluminum hydroxide fine particles are dispersed in a catalyst imparting agent for electroless plating is sucked by reducing the pressure inside the sintered metal tube, and the aluminum hydroxide fine particles are put into the surface pores of the sintered metal tube. Deposited. Thereafter, a palladium thin film (film thickness: 8 μm) was formed thereon by electroless plating. Next, the metal tube on which the palladium / silver alloy thin film was formed was dried at 120 ° C. for 10 hours and then heat-treated in a 500 ° C. argon stream for 5 hours to produce a hydrogen separation membrane.

Example 1
The hydrogen separation membrane produced in Production Example 1 was maintained at 500 ° C., a mixed gas of 2 atmospheres of hydrogen and 2 atmospheres of argon was placed outside the separation membrane, and the inside of the separation membrane was set to atmospheric pressure.

As a result, hydrogen flowed from the outside to the inside of the separation membrane at a flow rate of 22 ml / cm ² / min and separated. The argon flow rate was 0.06 ml / cm ² / min. Even after 100 hours, no change in permeate flow rate was observed.

  Thereafter, the cross section of the tube (hydrogen separation membrane) was observed with a scanning electron microscope and subjected to elemental analysis. As a result, no diffusion of iron, chromium, etc. was observed in the palladium layer.

Example 2
The hydrogen separation membrane produced in Production Example 2 was maintained at 500 ° C., a mixed gas of 2 atm hydrogen and 2 atm argon was placed outside the separation membrane, and the inside of the separation membrane was set to atmospheric pressure.

As a result, hydrogen flowed from the outside to the inside of the separation membrane at a flow rate of 20 ml / cm ² / min and separated. Argon permeation was not observed. Even after 100 hours, no change in permeate flow rate was observed.

  Thereafter, the cross section of the tube (hydrogen separation membrane) was confirmed with a scanning electron microscope and subjected to elemental analysis. As a result, no diffusion of iron, chromium or the like was observed in the palladium layer.

Example 3
The hydrogen separation membrane produced in Production Example 3 was kept at 500 ° C., a mixed gas of 2 atm hydrogen and 2 atm argon was placed outside the separation membrane, and the inside of the separation membrane was set to atmospheric pressure.

As a result, hydrogen flowed from the outside to the inside of the separation membrane at a flow rate of 24 ml / cm ² / min, and was separated. Argon permeation was not observed. Even after 100 hours, no change in permeate flow rate was observed.

  Thereafter, the cross section of the tube (hydrogen separation membrane) was observed with a scanning electron microscope and subjected to elemental analysis. As a result, no diffusion of iron, chromium, etc. was observed in the palladium and palladium / silver alloy layers.

Example 4
The hydrogen separation membrane produced in Production Example 4 was maintained at 500 ° C., a mixed gas of 2 atm hydrogen and 2 atm argon was placed outside the separation membrane, and the inside of the separation membrane was set to atmospheric pressure.

As a result, hydrogen flowed from the outside to the inside of the separation membrane at a flow rate of 23 ml / cm ² / min and separated. Argon permeation was not observed. Even after 100 hours, no change in permeate flow rate was observed.

  Thereafter, the cross section of the tube (hydrogen separation membrane) was observed with a scanning electron microscope and subjected to elemental analysis. As a result, no diffusion of iron, chromium, etc. was observed in the palladium layer.

Comparative Example 1
The hydrogen separation membrane produced in Comparative Production Example 1 was maintained at 500 ° C., a mixed gas of 2 atm hydrogen and 2 atm argon was placed outside the separation membrane, and the inside of the separation membrane was at atmospheric pressure.

As a result, hydrogen initially flowed from the outside to the inside of the separation membrane at a flow rate of 20 ml / cm ² / min, but the permeate flow rate decreased with time. After 24 hours, the hydrogen permeate flow rate was 15 ml. It decreased to / cm ² / min. Argon permeation was not observed.

  Thereafter, the cross section of the tube (hydrogen separation membrane) was observed with a scanning electron microscope and subjected to elemental analysis. As a result, remarkable palladium diffusion (estimated iron concentration: about 4%) was observed in the palladium layer.

Claims (7)

  Porous support made of sintered metal, thin film made of metal that does not form a solid solution with constituent elements of the sintered metal formed on the surface of the support, and thin film of palladium or palladium alloy formed on the thin film A hydrogen separation membrane comprising:   At least selected from the group consisting of metals, metal oxides, ceramics and their precursor components in the voids present on the surface of the porous support or on the thin film surface made of a metal that does not form a solid solution with the constituent elements of the sintered metal The hydrogen separation membrane according to claim 1, which is filled with one kind.   The hydrogen separation membrane according to claim 1 or 2, wherein the metal that does not form a solid solution with the constituent elements of the sintered metal is at least one selected from the group consisting of silver, gold, indium, tin, and lead.   A thin film made of metal that does not form a solid solution with the constituent elements of the sintered metal is formed on the surface of the porous support made of sintered metal, and then a thin film of palladium or palladium alloy is formed on the thin film. A method for producing a hydrogen separation membrane.   Group consisting of metal fine particles, metal oxide fine particles, ceramic fine particles, and precursor fine particles of these components in the voids existing on the surface of the porous support or on the thin film surface made of a metal that does not form a solid solution with the constituent elements of the sintered metal The production method according to claim 4, further comprising a step of filling at least one kind of fine particles selected from:   The method for producing a hydrogen separation membrane according to claim 4 or 5, wherein the metal that does not form a solid solution with the constituent elements of the sintered metal is at least one selected from the group consisting of silver, gold, indium, tin and lead.   A hydrogen-containing mixed gas is present on one side isolated by the hydrogen separation membrane according to any one of claims 1 to 3, and the hydrogen partial pressure on the other side is less than the hydrogen partial pressure on the hydrogen-containing mixed gas side. A method for separating hydrogen from a hydrogen-containing gas mixture.